ABSTRAK Bahan peningkat penetrasi merupakan zat tambahan yang membantu difusi obat melewati stratum korneum. Tujuan dari penelitian ini adalah untuk mengetahui efek penggunaan propilenglikol, DMSO, dan isopropil miristat dengan berbagai konsentrasi sebagai peningkat penetrasi dalam proses difusi asam kojat secara in vitro. Krim asam kojat dibuat dengan variasi konsentrasi propilenglikol, DMSO, dan isopropil miristat masing–masing 1%, 2%, 4%, dan 8% serta tanpa peningkat penetrasi. Pengujian stabilitas krim meliputi organoleptis, penentuan tipe emulsi, pH, dan viskositas. Uji difusi dengan alat sel difusi Frans menggunakan membran kulit tikus (Rattus novergicus) dan difusi asam kojat dalam cairan kompartemen reseptor pada interval waktu 0, 15, 30, 45, 60, 75, 90, 105, dan 120 menit diukur dengan menggunakan spektrofotometer UV. Hasil uji stabilitas menunjukkan tidak ada perubahan sebelum dan sesudah penyimpanan dipercepat tehadap organoleptis, penentuan tipe emulsi, dan pH tetapi viskositas berbeda sangat signifikan akibat variasi bahan dan konsentrasi peningkat penetrasi. Dari formula krim asam kojat yang mengandung DMSO 8%, propilen glikol 1%, isopropil miristat 8% yang diformulasi dapat dikategorikan stabil secara fisik dan paling efektif dibanding formula lainnya. Kata kunci: peningkat penetrasi, laju difusi, asam kojat. ABSTRACT Penetration of an enhancer is an additive that assist the diffusion of the drug through the stratum corneum. The purpose of this study was to determine the effect propylene glycol, DMSO, and with various concentrations of isopropyl myristate as penetration enhancers in the diffusion process of kojic acid in vitro. Kojic acid cream made with various concentration propylene glycol, DMSO, and isopropyl myristate, 1%, 2%, 4%, and 8% respectively, well as no penetration enhancers. Tests include organoleptic stability of cream, determining the emulsion type, pH, and viscosity. Diffusion test with tool diffusion frans cells using mouse skin membrane (Rattus novergicus) and diffusion in the liquid compartment kojic acid receptors on the time interval 0, 15, 30, 45, 60, 75, 90, 105, and 120 min were measured by using UV spectrophotometer. Stability test results showed there was no change before and after accelerated storage on organoleptic, determination of the type of emulsion viscosity and pH but differ significantly due to variations in ingredients and concentrations of penetration enhancers. Of kojic acid cream formula containing 8% DMSO, 1% propylene glycol, isopropyl myristate 8% which can be categorized formulated physically stable and most effective formula than the others. Key words: penetration enhancers, the rate of diffusion, kojic acid.